Molding core and method



oct. 13, 1925. 1,556,869

' T. E. MURRAY HOLDING C0 RE AND METHOD Filed Oct. 24. 1925 3Sheets-Sheet l noauto@ T. E. MURRAY HOLDING CORE ANiJ METHOD oct.13,1925.

f Illelllllllllll-ILIII 1925 3 Sheets-Sheet 2 Filed Oct. 24

oct. v12., 1925. 14556869 T. E. MURRAY HOLDING CORE AND lMETHOD Filedoct. 24. 1923 :s sheets-sheet :s

Patented O ct. 1 3,

UNITED STATES PATENT OFFICE.

moms E. mmv, or nnooxmm, NEW Yong.

' nomme conn AND nnrnon. l

Application mea october 24, 1923.- serm No. 670,423.

To all whom t may concern.'

Be 'it lmown that I, THOMAS E. MURRAY, a citizen of the United States,residing in the city of Brooklyn, county-of Kings, and

State of New Y ork','have invented certainnew `and 'useful Improvementsin Molding Cores and Methods, of which the following is a specification.Y

My invention aims to provide an improvement in cores and methodsfor'forming Figs. 4 and 5 are respectively aV longitudinal and atransverse section (on the line 5-5 of Fig. 4) and Fig. 6 isaperspective view, illustrating the applicationof al handle to the corefor pulling it out;

Fig. 7 is a longitudinal section of a modiied style of core;

Figs. 8 and 9 are longitudinal sections of a curved and a straight corerespectively witha modified style of pulling device; and

t Fig. v10 is-a transv erse section on the line -10,-10 of Fig. 9;

Fig. 11 is a longitudinal section showing .i

-a modified style of connection of the pulling device with thel core,and illustrating the latter partly withdrawn;

Figs. 12 and13 illustrate in longitudinal and transverse sectionrespectively, modifi- 'cations in the' composition or construction olthe core 'and in the pulling device;

f Figs. 14 and 15 are lon itudinal' and transverse sections respective yillustrating another style of v'reinforcement and ofthe pulling device;

Fig. 16 1s alongitudinal section illustratingstill another style ofreinforcement-- and ofthe pulling device;

" Figs. 17 and 18V are longitudinal and sure. y

cross-'sections respectively 'illustrating 'a slightly modified styleofpulling device;

Fig. 19 is a vertical .section through a conduit and manholeillustrating another style of pulling device;

Figs. 20and 21 are details of Fig. 19 in perspective Fig. 22 is anelevation of certain supporting blocks.

The core is made of sufficient strength to support the concrete or othermaterial molded around-it in plastic condition and of a material, inwhole or in part, which is resilient or capable ofl'being elongated andat 65 the same time contracted in cross-section,.-

such as rubber for example, and which will also return tosubstantiallyits original'form when the elongating strain is released.

Thus aiter the concrete has set and hardened,

a pull on the core will contract it, however slightly, sufficiently topermit its withdrawal. 'The pressure set up by the .casting of theplastic material around -it will depend on the size of the openingrequired, the 75 weight of 'thev plastic material, and the height of thelatter above the opening; and the material used must be of such strengthand dimensions as to withstand this pres-4 For example, the `core maybeJ a solid length of rubber, in which term I include not only amaterial which is all rubber, but also rubber compositions of varioussorts containing Or a tube of such rubber may be used with a suiicientlythick wall to support the pres# sure, or with supplementary supportingor reinforcing means. For example, `the tube 90V maybe reinforced by' antinner core, eitherv solid or tubular of spongy rubber or pther similar,materialA of a' lower grade and qual-v ity ;'or by some sort ofacollapsible mandrel such as a wire spiral or 'other flexible device. 95

Various-means may be provided, some of' whichare described hereinafterin detail, for l withdrawing'the core -and the inner mandrel orrein-forcement. For making lon to preventthe concrete from running downadulterantsor reinforcing mateopeningsor conduits,the core is provide 1nsec- 1 v tions connected end to end 1n such a way as ings are required,one above'another, such supports will space'.the cores properly.

These outside supports also permit the application of pressure fromwedges or otherwise Within the cores at the supported pointswithoutinjury to the tubular core or to the surrounding concrete.

In the form shown in Figs. 1 t0 6, the core is composed of an outer tube1 of comparatively high elasticity, such as a` good rubber composition,and an inner tube 2 'of less elasticity such, for example, as a cheaperrubber composition. vThe outer tube fits on the inner one with justsuiiicient looseness to permit relative movement, but not enough topermit the collapsing of the core substantially under the weight of theconcrete, The concrete 3 is poured around this core and allowed to setfor the required time. The core is then removed by a direct longitudinalpull as indicated in Fig. 2. This pull causes a slight `contraction ofthe .outer ,tube and, if the pull be great enough, of the inner tube. Atpoints remote from the application of the pull, the core will adhere tothe concrete until the strain is suiicient to cause such a contractionof the core at the near points as Will permit it to yield; and thisyielding will be progressive along the length of the core so as topermit the gradual elongation and withdrawal of the latter. The elonga-H tion necessaryto secure this resultneeds to .be only a small fractionof the total length of the tube.

A great variety of devices may be applied for pulling the core out. InFigs. 4 and 5 forexample', the outer .tube 1 is formed with lugs 4molded or vulcanized on its inner `face, in which are embedded plates 5extending beyond the end of the tube with openings through which alhandle 6 may be passed.

4In the modification shown in Fig. 7, the core is made of a solid tube 7reinforced with spiral and longitudinal cord fibers 8 a and9v-respectively.` For example the rubber com osition and the corereinforcement may be similarto those used in automobile tires.` lFig. 8illustrates what is equally true of thev other constructions, .that lthecore isiiexible so as to `permit the curving of it longitudinally forthe purpose of molding lbends or -other curved shapes to conduits..

This figure, and Figs. 9, 10 and 11, show the core made of a single tubewithout reinforcement,the composition and thickness l of the walls beingsuch as to provide sufficient'v strength for supporting the moldedmaterial and for maintaining their shape in cross-section on curves asin Fig. 8. The

pulling device in Figs. 8, 9 and 10 comprises a pair of chains 11-extending out of the end of the core to a handle 12 and connected t-oeyes'l?, fastened to the tube at intervals along its length. The chainsare arranged with a certain slack between the the slack is taken upbetween these two points of attachment of the chain. Thereafter thesecond section' of the core, between the second and the third set ofeyes is elongated and separated from the surrounding conduit; and so onto the end. Thus we avoid subjecting the core to extraordinarylongitudinal strain in order to contract the remote portion tliereof,and we permit the application of the method to cores of considerablelength, Vindependently of the strength of the material of which the coreis made. v

According to Fig. 11, a single chain 14 is used between `each pair offastening devices, the latter consisting of pins 15 with their ends heldin lugs 16 on the forward ends of separate sections.- 17 lof the tubing.The chains 14 are normally slack as illustrated. Ylhen the handle 18 ispulled the first section 17 of the core is withdrawn to an extentpermitted by the slack in the irst section of chain. By making the tubein separate sections 17, the sections do not have to be elongated to thefull length of the chain, the iirst section parting from the second andgoing along with the handle to an extent permitted by the frictionalengagement of its rear end with the surrounding'concrete 3.

According to Figs. 12 and 18 the tube 19 of rubber composition isreinforced by an embedded spiral 20 of flat wire or the like. This wireisjbentinward at suitable points to form loops 21 to which are iastenedthe branch cables 2 2 which lead to4 the main cable 23 by which the coreis pulled out ofthe conduit.

dis` ended by means ot a diaphragm or' plate 28 extending across thediameter of the spiral. The .rubber tube has ai slight play on the Wirespiral and the latter has a slight play on the .plate .26 so as topermit the yso necessary contractionof the core when its end (or the endof any section thereof) is pulled. Preferably the spiral is fixed to theplate 26 at intervals in its length as by welds 27. Tothe tube 24 arefastened at intervals eyes 28 which are connected .to chains 29. Theeyes pass freely through the coils of the wire and pullthe latter andthe plate 26 along with the tube. This spiral wire support may be curvedas in Fig. 8, or straight as desired.v

According to Fig. 16, a handle 30 is mounted on a tubular shank 31 aboutwhich the end of the core is clamped. The core in this case is a tube 32of rubber composition reinforced by an embedded spiral 33 of ine wire.-From the handle, strong wires )r cables 34 are connected to the tube atdifferent points .in its length. These wires may be always taut, or withpractically no slack, so as to pull simultaneously on successivesections of thetubing; though gen erally I prefer the arrangementpreviously describedwhere the pull is exerted on the tube sections oneafter the other.

In Figs. 17 and 18,*the tube 32 andrein'forcement. of spiral wire 33 arethe same as before. The pulling device comprises a pair of flexiblewires or cables 35 which pass through eyes 36 fastened on the tube andwhich have a' transverse'bend at these points and a certain amount ofslack between the points of attachment. With this arrangement thesections'of the tube will be pulled one after the other to withdrawthemfJ The slack 'in the wires 35 represents the desired limit of thestretch applied tothe rubber tube. The reinforcing wire spiral may beeither embedded in the rubber as shown or located within the tube inposition to hold the latter out against the pressure of the concretebeing molded. r

Fig. 19 shows the conduit opening into a manhole 37. The flexibility ofthe core permits it to be withdrawn at the manhole and turned .upward onto a takeup reel. The core in this case is formed yof one or moresections of rubber tubing lvsimilar to that shown in Fig.,1. It isreinforced, and

the withdrawal of it from the conduit is facilitated, by-means of blocks39 spaced close enough to support the tubing against the pressure of theconcrete,- but sufficiently far apart to permit it to bend in order toform bends in the conduit and in order to permit Withdrawal through. amanhole as illustrated. The blocks39 are spaced and connected togetherby means `of a flexible medium such as the chain 40 which passes throughthem` and to which they are attached by means of pins 41 (Fig. 20)passing through the blocks and through links of'vthe chain. At the endof each section,

as. for examplethe section 1a, at vthe left of Fig. 19, there 1s asleeve 42 of thick, comparatively soft, pliable rubber or other suit-Vable material vulcanizedor cemented into the end of the section andprojecting slightly beyond the end, the projectingl portion beingremovably fitted into the adjacent section 1b of the tube. The sleeve.42carries a transverse pin 43 to which the chain is attached. `When thesection 1b is pulled out it separates from thel wall of theconduitprogressively as described.

Fig. 19 shows the situation when it has been thus .separated and pulledout except for its rear end which embraces the sleeve 42. Thechain'between the rearmost block 39 and the pin 43 is slack, but to theright of the block 39 it is taut. A slight furtherl pull will remove theentire length vof the tubular section 1", and will tighten theintermediate length of chain so ,as to com- 'mence the correspondingpull through the pin 43 and sleeve 42 on thenext section 1a.

The blocks 39 are sufficient in size to hold the tubing distended'inuse. They make an easy fit in the tubing. When the tubing is I pulled,therefore, there' is contraction not only of the portion in advance ofthe block, but also a sufficient contraction of the portion surroundingthe block, asl indicated in Fig. 19, to free the tubing from theconcrete and thus to permit a further movement of the tubing and of theblock Within it. v

The blocks 39 have the additional Afunction of shaping the cross-sectionof the tube, which they lit loosely, but with suflicient accuracy tohold the tubing distended to substantially the contour of the block. ForeX- ample, Fig. 20 shows the blocks oblong in `cross-section and thetube of the same shape so as to mold a conduit fitted to take severalelectric cables alongside of each other without any waste of spacevertically. For a conduit of this shape it will be preferable to tubing,as to hold itin its original shape.

Ilhe tubing in fact may be formed of various'shapes in cross-section,according to the shape desired for the opening in the molded. material.And the same is true for the several other styles of dore referred toabove.

A further and important function of the blocks 39 isto provideforconveniently grip,-` ping the tube, so as to pull it not only from itsend but from intermediate points in its length. To this end the blocks39 co-operate with a clamp (Fig. 21)v composed of two members 44 withhandles, the members being hingedtogether at one side and clamped i witha swivel bolt 45 and thumb nut 46. The clamping members are applied, asat the right of Fig. 19, to the outside of the ,A tube in line with oneof the blocks. Preferably themembers 44 have reduced rear `ends 47 whichcontract the tube slightly at the rear of the block to get a morecertain pulling hold. By this means, the core. may be pulled out for alength corresponding to the distance between two blocks, or betweenseveral blocks, and the chnnp then shifted to tllef'iist block outsideof the end of the. mnduit and the operation repeated; the Yfree end ofthecore being taken u p on the reel. The connected blocks, therefore,serve toA reinforce the outer tube againstthe pressure of the concrete,to shape,l the eross-sertion ot' the core and to permit the operator totake hold of the core at successive points in its length without undulycollapsing-the tube. Various other means may be provided for serving thesaine function. l"or example, the inner tube 2 of Fig. 1 mayv be made ofoblong or other desired shape in cross-seetion, and may be made inseparate pieces with fiexible connections beween them like those betweenthe blocks of Fig. 20, and may thus serve the same purposes as theseblocks, constituting in effect hollow blocks.

In building a conduit, the concreteinay first be placed and leveled tothe height. of:y

the bottom of the opening, or may even be grooved along the line of theopening. The core will then be supported with proper alignment on theconcrete and additional concrete poured around the sides and over thetop of the mold. .I prefer, howevpr, to use supports for the core atintervals which will permit the plastic material to be cast under andaround the mold at one operation. Suitable supports are illustrated inFig. 22, consisting of blocks 48 forn'ied in segments adapted whenplaced together to surround the core l and having extensions 49 and 50at their sides and ends which serve4 to space them at proper intervalswhen a number of conduits are to be built through a single mass ofconcrete. For a single conduit, one of the segments 48 is placed in linebelow a part of the core carrying-one of the inside blocks 39; othersupporting blocks 48 being similarly placed at intervals along thelength of the core. Such blocks support the core at sufficiently closeintervals to hold it substantially straight; that is, to prevent saggingand, by .reason of the embracing side portions of the supports, toprevent lateral deflection. Thesupporting blocks are left in'as apermanent part of the finished structure. See Fig. 19.

Fig. 22 -illustrates the use of these s up ports fdr conduitsalongsidefotl each other and one above another., A pair of segmentsembraces a lower conduit andthe segments for the conduit abovearessupported directly on the first; their dimensions bein such as topreserve the .desired spacing. imilarly the segments at the sides areabutted directly against those first placed, being dimen 'sioned togive. the requiredlateral spacing.'

Instead of having the outer contour shown,

these blocks may be made substantially rectangular, or of other desiredshape.

In the present a plication I have claimed the invention broa ly in sofar as the tube is concerned, and also in connection with reinforcementsor mandrels and with supporting and withdrawing devices. In anotherapplication, Serial No. 679,521, I have de-l ticularity of detailcertain einbodinieitts of my invention, yet it is not to be understoodtherefrom that the invention is restricted to the lparticrlarembodiments disclosed. Various modifications maiv he made by thoseskilled in the art Without departure from the invention as defined inthe` following claims.

What I claim is 1. The method of molding conduits which. consists insetting in place an elastic tubular core of sufficient strength tosupport the external pressures of the molded material and of such acomposition that when extended in' one direction it will contract in atransverse directionl and when released it will resume its originalshape and holding said core in place by external means engaging the topof it, molding the material about said core' whilethus held in placeand, when the molded material has sufficiently hardened, pulling thecore longitudinally and thereby f contracting it sufiiciently to free itand to cause it t0 yield and to be withdrawn.

2. The method of molding conduits hav means engaging^ the tops thereof,molding the material about said cores .while thus held in place and,when the molded material has sufficiently hardened, pulling the coreslongitudinally and thereby cont acting them sufiiciently to free themand/ o to yield and to be withdrawn. 3. The method of moldingcondiiitshaving a multiplicity of ducts at different elecause them i vationswhich consists in 'setting in place elastic tubular cores of sufficientstrength to support the externalpressures of the molded l material andof such a 'composition that when extended in one direction they willcontract in a transverse direction and when released they will resumetheir, original shape and holding said cores in place in a properrelation to each other 'by external means engaging said cores, moldingthe -material about said cores while thus `held in of suoli acomposition that when extended in one direction it will contract in atransverse direction and when-released it will resume its -originalshape and holding said core in place by external means engaging thesides thereof to prevent lateral deflection, molding the material aboutsaid core while thus held in place and, when the molded material hassufficiently hardened, pulling the core longitudinally and therebycontracting it sufficiently to free it and to cause it to yield placeand, when the molded material has l sufficiently hardened, applying alongitudinal piill to the inside of the corev progressively along itslength and thereby contracting it suiiciently to-cause it to yield.

6. The method of molding conduits which 'consists in molding a plasticmaterial about an elastic c ore and applyinga longitudinal pull to theinside of the core progressively along its length and therebycontracting it sl'iiiiciently to causel it to yield and to belwithdrawn.

7. The method of molding conduits which consists in setting in place anelastic core, holding the same in place by external means, moldingaplastic material about the core and applying a longitudinalpull to theinside of the core progressively along its length and therebycontracting it sufficiently to cause it to yieldfand to be withdrawn.

8. A core for forming` openings in molded material, said core beingilexible, being of suicient strength to support the externa] pressuresof the molded material and being of such a composition that whenextended' in one direction it will contract in a transverse directionand when released will resuine its original shape in combination withpositioning means for holding said core 1n place by external engagementtherewith i and means for pulling said core by internal engagementtherewith to contract it transve i'sely.

9. A core for' formingopeninfrs in molded material, said corebeing'lexibsle, being of siiiiicient strength to support the externalpressuresof the molded material and being of such a composition thatwhen extended in one direction it will contract in a transversedirection and when released will resume its original shape incombination with positioning means for holding said core in place by"external engagement therewith andl means y for applying a longitudinalpull to the inside of. the core progressively, along its 'lengthtocontract` it transversely.

10. An elastic core for molding conduits in con'ibination. with meansfor applying -a longitudinal pull-to the inside o the core progressivelyalong its length to contract it transversely.

11. An elastic core for molding conduits in combination with externalmeans holding it in place and means for applying a longitudinal pull tothe inside of the core progressively along its length to contract yittransversely.

12. A core for molding conduits comprising in combination an outer tubeand an inner tube reinforcing the outer one., said core adaptedWhenpulled longitudinally to contract and permit withdrawal.

13. .A core for 'molding conduits comprising in combination an outertube of elastic composition and an inner tube of less elasticcomposition reinforcing the outer one, said core adapted when pulledlongitudinally to contract and permit withdrawal. A

14. A core for molding conduits comprising la tube of such a compositionthat when pulled longitudinally it will contract enough to yield andpermit withdrawal in combinaltion with means, engaging the core atintei-vals in its'length for pulling the same.

v for l5; A core for molding conduits comprisi ing a tube formed ofseparable sections and of such a 4composition that when pulledlongitudinally it will contractnenough to yield and permit withdrawal incombination with means engaging vthe core for pulling'v the same, saidpulling means 4adapted 'to l.exert a pull on the sections 4,insuccessive order.

16. A core -for molding conduits'comprising. a tube of such acomposition that when pulled longitudinally it will contract enoughtoyield and permit withdrawal in combination with means engaging thecore atintervals in its length for pulling the same,

along the inside of the core and engaged with the latter at intervals,with a certain -said pulling'means extending continuously v slackbetween points of engagement so as to said reinforcing members servingto assist exert a pull at different points in succession. the tube insupporting the molded material, 10 17. A vcore for molding conduitscompristo shape the erosssection of the tube, and to ing a tube of sucha composition that when provide supports at intervals for a pulling 5pulled longitudinally it will contract enough member applied to theoutside of the tube.

to yield and permit Withdrawal in combina- In Witness whereof, I havehereunto tion with reinforcing members Within thel signed my name. tubewith flexible connections between them, THOMAS E. MURRAY.

